What is music21?
Music21 is a set of tools for helping scholars and other active listeners answer questions about music quickly and simply. If you’ve ever asked yourself a question like, “I wonder how often Bach does that” or “I wish I knew which band was the first to use these chords in this order,” or “I’ll bet we’d know more about Renaissance counterpoint (or Indian ragas or post-tonal pitch structures or the form of minuets) if I could write a program to automatically write more of them,” then music21 can help you with your work.
How simple is music21 to use?
Extremely. After starting Python and typing "from music21 import *" you can do all of these things with only a single line of music21 code:
Display a short melody in musical notation:
converter.parse("tinynotation: 3/4 c4 d8 f g16 a g f#").show()
Print the twelve-tone matrix for a
tone row (in this case the opening of Schoenberg's Fourth String Quartet):
print (serial.rowToMatrix([2,1,9,10,5,3,4,0,8,7,6,11]) )
Convert a file from Humdrum's **kern data format to MusicXML for editing in Finale or Sibelius:
With five lines of music21 code or less, you can:
Prepare a thematic (incipit) catalog of every Bach chorale that is in 3/4:
for workName in corpus.getBachChorales():
work = converter.parse(workName)
firstTS = work.flat.getTimeSignatures()
if firstTS.ratioString == '6/8':
Google every motet in your database that includes the word ‘exultavit’ in the superius (soprano) part (even if broken up as multiple syllables in the source file) to see how common the motet's text is:
for motet in listOfMotets:
superius = motet
lyrics = text.assembleLyrics(part)
if 'exultavit' in lyrics:
webbrowser.open('http://www.google.com/search?&q=' + lyrics)
Add the German name (i.e., B♭ = B, B = H, A♯ = Ais) under each note of a Bach chorale and show the new score:
for thisNote in bwv295.flat.notes:
Of course, you are never limited to just using five lines to do tasks with music21. In the demos folder of the music21 package and in the sample problems page (and throughout the documentation) you’ll find examples of more complicated problems that music21 is well-suited to solving, such as cataloging the rhythms of a piece from most to least-frequently used.
Music21 builds on preexisting frameworks and technologies such as Humdrum, MusicXML, MuseData, MIDI, and Lilypond but music21 uses an object-oriented skeleton that makes it easier to handle complex data. But at the same time music21 tries to keep its code clear and make reusing existing code simple. With music21 once you (or anyone else) has written a program to solve a problem, that program can easily become a module to be adapted or built upon to solve dozens of similar (but not identical) problems.
Interested in learning more?
- Get Started with music21
- Browse the music21 documentation
- Download music21 from GitHub
- Get our latest news and updates at the music21 blog
- Read the Frequently Asked Questions list
- Sign up for the music21list mailing list through Google Groups.
An important milestone for music21 passed unnoticed by me a few weeks ago: ten years since the first time that code (well mostly documentation and tests) that still remains somewhere in the music21 codebase was run and did something useful (a scrambled loop for a composition project I was working on called Fine dead sound, after Faulkner). It seemed worth saying a bit about the history of the project and things learned along the way.
Music21 started as a Perl project -- the oldest code I can find that even vaguely resembles the current music21 comes from November 2003, a 30k Perl script to label a Bach chorale with Roman numerals and correct keys (I still need to publish the algorithm somewhere since I haven't seen a better one). It had no graphical output except using David Rakowski's Lassus font. I was able to get it back up and running and through the modern miracle of web fonts, everyone (except IE users) can play with the oldest music21 system at: http://www.trecento.com/test/lassus.cgi?num=260. If I remember correctly, chords in red had only a passing functionality, the small letters are the roots of chords and the second line of text is the locally active key. Pivot chords are labeled in brackets. This was done for an assignment in Avi Pfeffer's AI and Music class; others in my group had already produced the code (in C I believe) for removing passing tones from the score.
Version 2 is the first version of music21 since v.1 to make substantial changes in the code base that introduce backwards incompatibilities in order to make going forward faster and smoother. It doesn't change anything super fundamental à la Python 3's print function, so most code should still run fine, but definitely test in a separate environment before upgrading on any code you have that needs to run without problems. The system is still changing and more backward-incompatible changes could be included until v.2.1.
We have had 420 commits since the last release, so there is a lot that is new!
Substantial changes include:
- Offsets and quarterLengths are now stored internally as Fractions if they cannot be exactly represented as floating point numbers. A lot of work went into making this conversion extremely fast; you probably won't ever notice the speed difference, but you can now be sure that seven septuplets will add up to exactly a half note. For instance:
- >>> n = note.Note()>>> n.duration.appendTuplet(duration.Tuplet(3,2))>>> n.fullName'C in octave 4 Quarter Triplet (2/3 QL) Note'>>> n.quarterLengthFraction(2, 3)>>> n.quarterLengthFloat # if you need it...0.6666666666666666
- Converter structure has been overhauled for more easily adding new converters in the future. If you've wanted to write a converter or already have one for a format not supported but have been daunted by how to include it in music21 now is a great time to do it. Speaking of which...
- MEI format is supported for import (thanks to Chris Antila and the ELVIS team at McGill university for this great enhancement)
- Python 2.6 is no longer supported. All tests and demos pass and run on Python 2.7, 3.3, and 3.4. (3.2 and older are not supported)
- FreezeThaw on Streams works much better and caching loaded scores works great (some of this was included in 1.9, so definitely upgrade at least to that.
- Lots of places that used to return anonymous tuples, now return namedtuples for more easily understanding what the return values mean.
- Integrated Travis-CI testing and Coverage tests will keep many more bugs out of music21 in the future.
- Many small problems with Sorting and stream handling fixed.
- Corpus changed: for various licensing reasons, v.2.0 does not include the scores from the MuseData corpus anymore. This change mostly affects Haydn string quartets and Handel's Messiah. However, new replacement scores are being included and 2.1 will have as many great works as before. The MuseData scores are still available online. MuseData is now a deprecated format and no further testing on it will be conducted; only bug fixes that are easily implemented will be accepted.
- music21 is now available under the BSD license in addition to LGPL!
- Stream __repr__ now includes a pointer rather than a number if .id is not set. This change will make filtering out doctests easier in the future.
- TinyNotation no longer allows for a two-element tuple where the second element is the time signature. Replace: ("C4 D E", "3/4") with ("tinynotation: 3/4 C4 D E")
- Obscure calls in SpannerBundle have been removed: spannerBundle.getByClassComplete etc.
- Convenience classes: WholeNote, HalfNote, etc. have been removed. Replace with Note(type='whole') etc.
- Old convenience classes for moving from Perl to Python (DefaultHash, defList) have been removed or renamed (defaultlist)
- Articulations are marked as equal if they are of the same class, regardless of other attributes.
- common.almostLessThan, etc. are gone; were only needed for float rounding, and that problem is fixed.
- duration.aggregateTupletRatio is now aggregateTupletMultiplier, which is more correct.
- scala.ScalaStorage renamed scala.ScalaData
- common.nearestMultiplier now returns the signed difference.
- layout -- names changed for consistency (some layout objects had "startMeasure" and some "measureStart" - now they're all the same); now all use namedtuples.
- rarely used functions in Sites, base, Duration, SpannerStorage, VariantStorage, have been removed or renamed. I'd be surprised if these affect anyone outside the development team.
- common.mixedNumeral for working with large rational numbers
- common.opFrac() optionally converts a float, int, or Fraction to a float, int, or Fraction depending on what is necessary to get exact representations. This is a highly optimized function responsible for music21 working with Fractions at about 10x the speed of normal Fraction work.
- Rest objects get a .lineShift attribute for layout.
- staffDetails, printObject MXL had a bug, writing out "True" instead of "yes"
- staffLines is now an int not float. (duh!)
- better checks for reused pointers.
- lots of private methods are now ready for public hacking!
- Lyric.rawText() will return "hel-" instead of "hel" for "hel-lo".
I am a researcher within the Performing Arts Medicine Association. I was interested in looking at Beethoven's use of range over time in his piano sonatas. Although several previous studies have looked at the question of how Beethoven's compositions were affected by his hearing loss, the results were far less than conclusive. A study in the British Medical Journal counted the notes in the first movements of the first violin parts of Beethoven's string quartet's by hand. For a number of reasons, I thought it might be better to look at the piano sonatas, including that Beethoven wrote more piano sonatas than he did string quartets and symphonies, so the statistical power would be greater. Counting all of the notes in Beethoven's piano sonatas by hand would be a Herculean task for sure, but fortunately with scores available from the Center for Computer Assisted Humanities and music21 sufficient coding skills would do the job.
In addition to the number of high notes, I was also interested in Beethoven's overall use of range, the average note, average frequency, number of measures with high notes, and in calculating values based on the number of notes, as well as weighting those measures by the duration of notes. The methods available in music21 allow the collection of this data very quickly. To collect the majority of the data I needed from all 103 movements of Beethoven's piano sonatas, count over a quarter million individual notes, and organize the data into sonatas, and separating the data by movement number, takes about 11 minutes.
Some Interesting Findings
Beethoven's use of high notes was lowest around 1800 (for all the graphs below, the colors within the dots represent the Sonata Numbers, going from red to purple from 1-32):
The average frequency of each sonata follows a similar trend:
In general, as there are more notes per measure, there are more high notes per measure. This trend does not hold many of the sonatas written before 1802.
Also, the relationship between the use of high notes, and the average frequency was different between the earlier and later sonatas:
Technology like music21 is an invaluable tool for the empirical study of musicology. Relatively quickly, data gathered can be used to analyze the possible relationships between Beethoven's use of high notes and his overall range, and compare that with what we understand about his hearing loss. These data suggest that Beethoven was significantly affected by his hearing loss, though it seems that sometime around 1802 he developed strategies to cope with his progressing disability.
While everyone says that in Python you can import a module inside a function without it going through the overhead of actually reimporting, there is some real overhead still, especially if the function is called a lot of times:
How can I contribute?
Music21 is a rapidly-progressing project, but it is always looking for researchers interested in contributing code, questions, freely-distributable pieces, bug fixes, or documentation. Please contact Michael Scott Cuthbert (cuthbert at mit.edu), Principal Investigator.
The development of music21 has been supported by the School of Humanities, Arts, and Social Sciences at M.I.T., the Music and Theater Arts section, and generous grants from the Seaver Institute and the NEH/Digging-Into-Data Challenge. Further donations to the project are always welcome.